This invention pertains generally to convertible roof systems for automotive vehicles and more specifically to a composite roof rail used in the convertible roof system.
Traditional soft-top convertible roofs for automotive vehicles typically employ a top stack mechanism that is operable between extended (raised) and retracted (stowed) positions. The top stack mechanism typically employs three, four or five roof bows, having an inverted U-shape spanning transversely across the vehicle for supporting a vinyl, canvas or polyester fabric pliable roof cover. A number one roof bow is mounted to a pair of front roof rails and is typically latched to the stationary front header panel of the automotive vehicle body disposed above the front windshield. A number two bow is typically mounted to a pair of center roof rails which are pivotally connected to the front roof rails. Furthermore, the number three, four and any additional optional roof bows are commonly mounted to a pair of rear roof rails which are pivotally coupled to the center roof rails. The roof cover can also have a hard or rigid portion along with the pliable portion. For example, reference should be made to U.S. Pat. No. 5,429,409 entitled “Convertible Top,” which is incorporated by reference herein. Most traditional convertible roofs are stowed in a boot well or stowage compartment that is located aft of a passenger compartment in the vehicle. A boot or tonneau cover is then used to cover the boot well and conceal the convertible roof from view and/or protect the stowed roof from the environment.
The roof rails in the top stack mechanism are typically made of a die cast aluminum or magnesium alloy or steel. These roof rails can be heavy and/or expensive to make. Each roof rail is typically made separately and adjacent roof rails are later pivotally coupled together to form a portion of the top stack mechanism. Each of the roof rails is specifically designed for the particular application or automotive vehicle on which the top stack mechanism is employed.
In accordance with the present invention, the preferred embodiment of a convertible roof system uses a top stack mechanism that includes at least one composite roof rail that is made from different materials. The use of differing materials for the composite roof rail can provide for a less expensive roof rail with an improved strength to weight functionality. When a polymeric material is utilized, the polymeric portion of the composite roof rail can be injection molded or extruded thus providing a simple manufacture of the composite roof rail. The use of a polymeric material also facilitates the contouring of the exterior shape of the composite roof rail and can include the integration of a trim garnish feature on the interior and a seal retaining feature on the exterior of the composite roof rail thereby simplifying construction and minimizing the number of parts.
In accordance with another aspect of the present invention, a convertible roof system for an automotive vehicle includes a top stack mechanism that utilizes at least one composite roof rail that is formed of at least two different members that are attached together. The use of two different members facilitates one of the members being designed to withstand the stresses and strains in forming a portion of a coupling joint that couples the composite roof rail to another component of the top stack mechanism. The other member can then be designed to provide a desired exterior profile of the composite roof rail while reducing the weight and cost of the roof rail. The composite roof rail allows for the use of universal connecting pieces for the roof rail. A central portion of the roof rail is designed specifically for the application on which the convertible roof system is to be utilized while the end or connecting portions of the composite roof rail are selected from a group of universal roof rails. The universal connecting portion of the roof rail is chosen to provide a desired movement of the roof rail relative to the other components of the top stack mechanism to which it is coupled. The use of universal connecting pieces is advantageous by reducing the tooling costs associated with designing connecting pieces specific for each roof rail for each automotive vehicle upon which a convertible roof system is desired to be utilized.
In still another aspect of the present invention, the convertible roof system uses as top stack mechanism wherein first and second roof rails are formed around a connector that pivotally couples the first and second roof rails together. The two roof rails and connector can be produced in a common or single mold that is designed for the two roof rails and the connector. The molding of the two roof rails around the connector that pivotally couples them together is advantageous over the typical convertible roof systems in that the roof rails are removed from the mold already pivotally coupled together thereby simplifying the assembly of a top stack mechanism.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.